1. Field of the Invention
The present invention relates to a product quality test in a winding step of the entire manufacturing process of a deflection yoke, which is a core part of a display device employing a cathode ray tube such as a color TV or a monitor, and in particular, to a magnetic field measuring system of a deflection yoke that can predict screen characteristics in light of coil characteristics and can perform a total inspection of the coil characteristics and a coil grouping to enhance a product quality and a productivity by introducing a magnetic field measuring system in the process of manufacturing a horizontal deflection coil and a vertical deflection coil, which are core parts of a deflection yoke.
2. Description of the Prior Art
In general, the deflection yoke is classified into a saddle-toroidal type, a saddle-saddle type, etc., and functions to accurately deflect electron beams scanned from an electron gun to a fluorescent film coated on a screen of a cathode ray tube.
FIG. 1 shows a construction of a conventional deflection yoke. As shown in FIG. 1, a deflection coil 100 comprises a horizontal deflection coil and a vertical deflection coil, and functions to change the progressing direction of electron beams from a cathode ray tube (CRT) of a TV. Here, the horizontal deflection coil is seated around an internal periphery of a separator 200 formed in a horn shape, while the vertical deflection coil is seated around an external periphery of the separator 200.
The deflection coil 100 for horizontally and vertically deflecting the progressing direction of electron beams from a CRT is wound several times by a winding machine in a saddle shape so as to be seated on internal and external peripheries of the separator 200. FIG. 2 shows the deflection coil 100 comprising an upper flange 110 section including upper pinholes 111, a lower flange section 120 including a lower pinhole 121, and a body 130 located between the upper flange section 110 and the lower flange section 120.
Here, the upper pinhole 111 and the lower pinhole 121 function to smoothly adjust convergence by varying an inductance value and an impedance value to properly control the deflected degree of the electron beams.
The deflection yoke constructed as above is mounted on a neck of the CRT to deflect the electron beams R, G, B emitted from an electron gun of the CRT and determine the scanning positions of the electron beams on a screen, when a saw tooth wave pulse is applied to the horizontal deflection coil and the vertical deflection coil, and when magnetic fields are subsequently generated according to the Fleming""s left-hand rule.
Here, the deflection force deflecting the electron beams R, G, B is mainly generated by the horizontal deflection coil and the vertical deflection coil among all the parts of the deflection yoke.
The horizontal and the vertical deflection coils play a significant role of realizing colors by receiving a signal from a control section of a display device and by deflecting the electron beams to desired positions. Of course, the quality as well as the functionality is a significant factor to be considered for evaluating a deflection yoke. Thus, it would be absurd to discriminate the parts of the deflection yoke in light of their functionality alone. However, it is obvious that the horizontal and vertical deflection coils perform the most essential function of the deflection yoke.
Therefore, it is one of the most important step in the entire process of manufacturing the deflection yoke to quantize the characteristics of the horizontal and the vertical deflection coils by using the relationship between the degree of generating the magnetic fields and the screen characteristics.
The process of manufacturing the horizontal and the vertical deflection coils, which are core parts of the deflection yoke in general, comprises the step of molding magnetic wires by means of a winding machine. Here, the winding machine includes a winding zig suitable for realizing the characteristics of diverse kinds of deflection yoke.
The quality of the coils manufactured through the above step can be evaluated by roughly measuring the magnetic fields or based on the screen characteristics after manufacturing the deflection yoke. However, the aforementioned two methods are capable of sampling tests only but insufficient to evaluate the entire products that have been manufactured. Further, the evaluation based on the screen characteristics has a drawback of failing to test the characteristics of the coils only due to the fabricating nature and influence of other minor materials.
In general, the conventional method of testing characteristics of the horizontal and the vertical deflection coils is to evaluate screen characteristics that is actually displayed after completing manufacture of the deflection yoke and to determine the coil characteristics based on the evaluated result. However, this method consumes a considerable period of time for manufacturing the deflection yoke, and subsequently increases the time for feeding back faults in its characteristics, if found any, thereby causing a managerial loss.
Under these circumstances, a compact managing method has been recently suggested to sample coils by using the relationship between the magnetic field characteristics and the screen characteristics, and to measure the magnetic fields of the sampled coils. If the measured magnetic fields are within a set standard, manufacture of the coils is proceeded with. However, this compact managing method has a limit of inspecting the sampling, thereby posing a problem of failing to prepare a proper countermeasure against a feasible dispersion in the manufacturing process.
It is, therefore, an object of the present invention to provide a magnetic field measuring system of a deflection yoke that is related to a product quality test in a winding step of the entire manufacturing process of a deflection yoke, which is a core part of a display device employing a CRT such as a color TV or a monitor, and in particular, to a magnetic field measuring system of a deflection yoke that can predict screen characteristics in light of coil characteristics and can perform a total inspection of coil characteristics and a coil grouping to enhance a product quality and a productivity by introducing a magnetic field measuring system in the process of manufacturing a horizontal deflection coil and a vertical deflection coil, which are core parts of a deflection yoke.
In other words, an object of the present invention is to introduce a coil measuring system into a winding system for manufacturing coils as well as to establish a system capable of a total inspection of coil characteristics by using the coil measuring system.
To achieve the above object according to one aspect of the present invention, there is provided a winding zig for measuring magnetic fields of a deflection yoke, comprising: a plurality of magnetic field sensors mounted inside of the A-shaped winding zig; a digital signal generator for receiving output signals from the magnetic field sensors for sensing magnetic field characteristics of a deflection coil wound around the A-shaped winding zig, and amplifying and converting the received signals to digital signals; a digital signal interface for converting data outputted from the digital signal generator to serial data; and a radio signal transmitter for receiving the signals processed to serial data by the digital signal interface, converting the received signals to radio signals, and transmitting the converted signals.
The digital signal generator in the winding zig for measuring magnetic fields of a deflection yoke comprises: amplifiers matched with each magnetic field sensor wound around the A-shaped winding zig for amplifying the signals sensed by the magnetic field sensors to a predetermined gain, and outputting the amplified signals; and A/D converters matched with each amplifier for converting the amplified signals to digital data.
According to another aspect of the present invention, there is provided a winding zig for measuring magnetic fields of a deflection yoke, comprising: a plurality of magnetic field sensors installed inside of the A-shaped winding zig; a digital signal generator for receiving output signals from the magnetic field sensors that sense magnetic field characteristics of a deflection coil wound around the A-shaped winding zig, amplifying the received signals, and converting the amplified signals to digital signals; a digital signal interface for converting the data outputted from the digital signal generator to serial data; an independent current source for supplying a driving current to drive the magnetic field sensors; a radio signal transmitter for receiving signals processed as serial data by the digital signal interface, converting the received signals to radio signals, and transmitting the converted signals; and an independent voltage source for supplying a driving voltage to drive the digital signal generator and the digital signal interface.
To achieve the above objects, there is also provided a magnetic field measuring system of a deflection yoke, comprising: a plurality of magnetic field sensors installed inside of an A-shaped winding zig; a digital signal generator for receiving output signals from the magnetic field sensors that sense magnetic field characteristics of a deflection coil wound around the A-shaped winding zig, amplifying the received signals, and converting the amplified signals to digital signals; a digital signal interface for converting the data outputted from the digital signal generator to serial data; an independent current source for supplying a driving current to drive the magnetic field sensors; a radio signal transmitter for receiving signals processed as serial data by the digital signal interface, converting the received signals to radio signals, and transmitting the converted signals; a radio signal receiving section for receiving magnetic field measuring data of a radio signal type transmitted through the radio signal transmitter; a data parallel processor for receiving the data received through the radio signal receiving section, converting the received data to parallel data, and processing the converted data by reference to a predetermined index in accordance with an associate relationship between screen characteristics and magnetic field values; and a liquid crystal display for visually displaying the data processed by the data parallel processor to an inspector or a worker.
According to another aspect of the present invention, there is provided a magnetic field measuring system of a deflection yoke, comprising: a plurality of magnetic field sensors installed inside of an A-shaped winding zig; a digital signal generator for receiving output signals from the magnetic field sensors that sense magnetic field characteristics of a deflection coil wound around the A-shaped winding zig, amplifying the received signals, and converting the amplified signals to digital signals; a digital signal interface for converting the data outputted from the digital signal generator to serial data; an independent current source for supplying a driving current to drive the magnetic field sensors; a radio signal transmitter for receiving signals processed as serial data by the digital signal interface, converting the received signals to radio signals, and transmitting the converted signals; a radio signal receiving section for receiving magnetic field measuring data of a radio signal type transmitted through the radio signal transmitter; a data parallel processor for receiving the data received through the radio signal receiving section, converting the received data to parallel data, and processing the converted data by reference to a predetermined index in accordance with an associate relationship between screen characteristics and magnetic field values; an image processing controller for receiving data processed by the data parallel processor, and realizing the processed data into images of three or two dimensions; and a liquid crystal display for visually displaying the images of three or two dimensions in accordance with an associate relationship between screen characteristics and magnetic field values to an inspector or a worker.